Transformer.



PATENTED'MAR. 29, 1904.

Z. 5 Z on a w a H m .{Wli t B n H 7 w a n m WWY I a .wa W Wl .W F u I m w W. A. HALL. TRANSFORMER. APPLICATION FILED snr'r. 29. 1902.

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UNITED STATES Patented March 29, 1904. V

PATENT OFFICE.

l/VALTER A. HALL, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

TRANSFORMER.

SPECIFICATION forming part of Letters Patent No. 755,766, dated March 29, 1904..-

Application filed September 29, 1902. SeIiaI No. 125,214. (No model.)

To all whom it may concern:

Be it known that I, WALTER A. HALL, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and usefulImprovements in Transformers, of which the following is a specification. I

This invention relates to improvements in electrical transformers; and its object is to enable transformers of large size to be economically' constructed having a minimum mean-length turn of copper, a magnetic circuit of minimum length and maximum crosssection, and an abundance of ventilating or oil-circulating spaces.

To this end the invention consists in the construction and arrangement of parts hereinafter described, and particularly pointed out in the claims.

In the accompanying drawings, Figures 1 and 2 areside elevations of the iron laminae of which the core of the transformer is composed. Fig. 8 is a side elevation of the core and the coil. Fig. 1 is a top plan view of the same. Fig. 5 is a cross-section of the coil. Fig. 6 is a top plan view of the core and the 'casing or box-with the cover removed; and

Fig. 7 is a diametrical cross-section of the casing, showing the core and coil in elevation.

In building up the core of my transformer two differentsizes of sheet-iron laminae are used. Each complete lamina is composed of,

plus the width ofthe winding-space. smaller U-shaped pieces have legs 6 7, whose width is one-half that of thelegs 1 2 of the large pieces. I 1 piece 9 are both of the same width as the legs The integral end 8 and the end 6 7." The total length of this smaller lamina The length of the end piece 5 is equal to the width of one leg The is less than that of the larger one by an amount equal to thewidth of the end 4. The winding-space 10 is of the same dimensions as the winding-space 3. The larger laminae after suitable treatment are laid together coincidentlynntil the cross-section of each leg is square. The mass is then pressed in apowerful hydraulic or other press and is then clamped in any suitable manner to retain it in shape. The smaller laminae are laid up until the thickness of the legs 6 7 is the same as that of the legs 1 2 of the larger laminae.

To form the core of the transformer; two bundles A A of the largerlaminae are placed edge to edge in the same plane, and two bundlesrB B of the smaller laminae are placed at right angles to the bundles A A, one edge of each bundle B B abutting against the meeting edges of the bundles A A and the bottoms of the winding-spaces 3 10 being all in the same plane. The core thus formed has a central leg. cruciform in cross-section, two opposite legs square in cross-section, and two opposite legs rectangular in cross-section.

The coil for this transformer is preferably composed of two portions, an inner octagonal portion O,composed of one or more secondary windings 11 12,and an inclosing primary winding 13, and an outer portion D, consisting of a primary winding 14, surrounded by one or more secondary windings 15 16, all wound in substantially square form with rounded corners 17 of large radius. r The inner portion O fits closely upon the cruciform central leg of the core, leaving triangular ventilating oroilcirculating spaces 18 at the corners, and the combined thickness of the two portions just ter the coil has been slipped over the central 1 leg of the core and seated on the bottom of the winding-space in each branch of said core the end irons 2O 21. are placed in position, and the core and coil are assembled in a box or casing 22, which is filled with oil. In order to secure them in place, the box has internal lugs 23 on its sides,between which the edge of the core branches are received. 7 Wooden wedges 24: are driven in between the lugs and the core to fasten the latter securely. On the bottom of the box are lugs 25, preferably tapered, to compress the laminae as the bottom edges of the core enter between said lugs. The cover 26 has lugs 27, similar to those on the bottom of the box, and when the cover is drawn down by suitable fastening devices, such as the eyebolts 28, screwed into lugs 29 on the box, the lugs 27 clamp the core at the top.

It will be seen that by means of this construction I obtain several advantages:

First. A maximum cross-section of magnetic circuit for a minimum length of same, thereby reducing to a minimum the weight of iron and the consequent turns of copper required for a given core loss. It will be noted that in the smaller branches of the core the mean length of the magnetic circuitis less than that in the larger branches in the ratio of ten to eight, the resultant of the entire magnetic circuit being nine and one-third instead of ten, which would be the case were all of the laminations laid in one direction, as in the case of a common shell-type transformer.

Second. A core which in effect corresponds to what is commonly known as the shell type design, but having an advantage over that design in that it permits pressing of the iron before assembly and obtains thereby a maximum effective cross-section of iron in a given space.

Third. It presents for the central leg, upon which are assembled the windings, an octagonal perimeter, a figure which as closely approximates a circle as is commercially practicable, thereby allowing the magnetic circuit to be linked by a minimum mean-length turn of copper for a given cross-section of core so inclosed. This octagonal center presents a further advantage in that large conductors may readily be made to conform closely to its contour in winding, permitting a maximum amount of copper to be wound in a given thickness of coil without the necessity of applying excessive tension injurious to insulation, which would be required on a form having sharper angles.

Fourth. A number of oil-channels of considerable cross-section and short length between core and windings and between parts of the winding, promoting a rapid circulation of oil and dissipation of heat. The introduction of oil-channels between windings is effected without loss of winding-space betweenthe leg-irons, while those between the core and coils are obtained with a slmilar saving in winding-space and at the same time without increasing the length of copper required.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

l. A transformer-core consisting of four bundles of iron laminae arranged radially to abut each other at the center of the core, each bundle constituting a magnetic circuit, two of the bundles of laminae directly abutting each other, the second two bundles abutting the opposite sides of the joint between the directlyabutting laminae, the legs of the second two bundles of laminae being of less width than the legs of the directly-abutting bundles of laminae, in order to make the center of the core cruciform in cross-section.

2. A transformer-core consisting of oppd sitely-disposed bundles of iron laminae constructed and arranged radially to fill the cen' ter of the core with a mass of laminated iron polygonal in cross-section to form coolingspaces in the periphery of the center of the core.

3. A transformer-core consisting of a plurality of bundles of iron laminae arranged radially and closely abutting each other at the center to make the center of the core a solid mass of laminated iron, the construction and arrangement of the bundles contributing to form a core having a periphery with reentrant angles, whereby cooling-spaces are provided between the core and the coils thereon.

4:. A transformer-core consisting of a plurality of bundles of iron laminae arranged radially to abut each other at the center, the width of the legs of some bundles being less than that of the legs of the other bundles, whereby cooling-spaces of large cross-section and short length are formed between the center of the core and the coils thereon.

5. A transformer-core consisting of a plurality of U-shaped bundles of iron laminae assembled in radial planes, the legs of certain bundles being smaller in cross-section than the legs of other bundles in order to provide the center of the core with an irregular periphery.

6. A transformer-core consisting of two bundles of iron laminae abutting each other in the same plane and having the space between the legs equal to the width of a leg, and two bundles of iron laminae in the same plane with each other abutting the first two bundles of laminae on opposite sides of their joint and having the same space between the legs as the first two bundles, but the width of the legs one-half that of the first two bundles.

7. A transformer-core consisting of two bundles of iron laminae abutting each other, and two bundles of laminae abutting the opposite sides of the joint between the first two bundles, the second two bundles being of such thickness that they do not extend the full combined width of the first two abutting bundles.

8. A transformencore consisting of two bundles of iron laminae abutting each other, and two bundles of iron laminae abutting the opposite side of the joint between the first two' bundles, the second two bundlesbeing of such thickness that they do not extend the full combined width of the first two abutting bundles, and the width of the second two bundles being less than that of either of the first two bundles, whereby the four bundles form a substantially symmetrical figure in crosssection. v

9. A transformer-core consisting of a plurality of compressed bundles of 'U-shaped laminae retained in compression and arranged radially to abut each other to form a polygonal figure in cross-section through the center of the core.

10. A transformer-core consisting of a plurality of bundles of iron laminae arranged radially to abut each other at the center of the core, all the laminae in each bundle being substantially duplicated or coextensive and pressed together, whereby the center of the core consists of a maximum amount of laminated iron.

11. A transformer-core of substantially the shell-type design, consisting of a plurality of bundles of iron laminae abutting each other at the center of the core, the laminae in each bundle being pressed closely together in order to obtain a maximum effective cross-section of iron in a given space.

12. A transformer having a coil made in two concentric portions, the inner one polygonal, and the outer one square with rounded corners,-whereby ventilating-spaces are left between said portions.

18. A transformer-core composed" of two U-shaped branches lying in the same plane, and presenting a given length of magnetic circuit, and two U-shaped branches lying in a plane at right angles thereto, and presenting a shorter magnetic circuit.

In witness whereof I have hereunto set my hand this 26th day of September, 1902.

WALTER A. HALL.

Witnesses:

DUGALD MoK. MOKILLOP, JOHN A. MoMANUs. 

